To delineate the biochemical events associated with the development of opiate tolerance in the amygdaloid region of the brain. We plan to use a mirror focus preparation in which unilateral intra-amygdala morphine administration causes epileptiform spikes in the amygdala of both hemisphere but produces tolerance only at the injection site. To separate the direct biochemical effect opiates have on amygdaloid cells from secondary biochemical changes resulting from the shared bioelectric responses of both amygdaloid regions, we plan to compare changes in neurotransmitter-receptor activity in the amygdala bilaterally following chronic unilateral treatment with morphine. BIBLIOGRAPHIC REFERENCES: Teitelbaum, H., Blosser, J. and Catravas, G. Bilateral electroencephalographic response and unilateral tolerance to unilateral intracerebral morphine injections. Nature, 260, 158-159, 1976. Teitelbaum, H., Lee, J.F. and Levin, S.C. Cross tolerance between morphine and cholinergic blocking drugs microinjected into the anterior amygdala. Fed. Proc. Abst. 1977.